Minimal API trace missing http.route tag

[andreasuvoss]

Bug Report

Packages used:

• OpenTelemetry.Exporter.Console 1.4.0-rc.4
• OpenTelemetry.Extensions.Hosting 1.4.0-rc.4
• OpenTelemetry.Instrumentation.AspNetCore 1.0.0-rc9.13

Runtime versions:

• net6.0
• net7.0

Symptom

The resulting trace from calling an endpoint mapped using Minimal Api does not contain the http.route tag, however the tag is present when calling an endpoint defined in a classic controller.

What is the expected behavior?

The trace contains the tag http.route for endpoints created with the Minimal API syntax.

Activity.Tags:
    ....
    http.route: works/{id:int}
    ....

What is the actual behavior?

The trace does not contain the http.route tag for endpoints created with the Minimal API syntax.

Reproduce

With the code below call endpoint /does-not-work/1234 and observe that http.route is not present among the tags in the console output. Do the same for /works/1234 and observe that the http.route tag is present among the tags in the console output.

using Microsoft.AspNetCore.Mvc;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddControllers();

builder.Services.AddOpenTelemetry().WithTracing(b =>
{
    var resourceBuilder = ResourceBuilder.CreateDefault()
        .AddService("MinimalExample", null, "0.0.1");
    b.SetResourceBuilder(resourceBuilder)
        .AddAspNetCoreInstrumentation()
        .AddConsoleExporter();
});

var app = builder.Build();

app.MapControllers();

app.MapGet("/does-not-work/{id:int}", (int id) => "Trace without http.route");

app.Run();

[ApiController]
public class TestController : ControllerBase
{
    [HttpGet]
    [Route("/works/{id:int}")]
    public IActionResult GetTest(int id)
    {
        return Ok();
    }
}

<Project Sdk="Microsoft.NET.Sdk.Web">
    <PropertyGroup>
        <TargetFramework>net7.0</TargetFramework>
        <Nullable>enable</Nullable>
        <ImplicitUsings>enable</ImplicitUsings>
    </PropertyGroup>

    <ItemGroup>
      <PackageReference Include="OpenTelemetry.Exporter.Console" Version="1.4.0-rc.4" />
      <PackageReference Include="OpenTelemetry.Extensions.Hosting" Version="1.4.0-rc.4" />
      <PackageReference Include="OpenTelemetry.Instrumentation.AspNetCore" Version="1.0.0-rc9.13" />
    </ItemGroup>
</Project>

Additional Context

I have looked a bit into the source of OpenTelemetry.Instrumentation.AspNetCore and it seems like the OnMvcBeforeActionEvent never occurs when calling the endpoint created with Minimap API syntax. All other expected tags seem to be present.

The issue seems to be the same with both net6.0 and net7.0.

[vishweshbankwar]

Thanks for reporting. The issue is already being tracked with #3461. Closing this one.